Field of the Invention
The present invention relates to a variable intake system, and more particularly, to a variable intake system with a variable valve, an opening degree of which is varied depending on a variation in air intake amount of a vehicle engine.
Description of Related Art
In general, in a variable intake system of a vehicle engine, air which is drawn in through an air duct is filtered by a filter disposed in an air cleaner, and a plurality of air ducts are provided to compensate for insufficient amount of intake air when the engine is operated at a high-speed and high-load region.
Air is sucked into the engine through an intake system, and engine noise is discharged to an air inlet of the air duct through the intake system.
Therefore, the intake system is generally designed to minimize flow resistance of the air flowing into the engine to improve engine output, and minimize a degree of engine noise that is transmitted to the inlet of the air duct.
Noise inside the vehicle results from various noises such as road noise, radiated sound from the engine, wind noise, and vibration in a vehicle body structure, and the aforementioned noise changes proportionally to an engine RPM and a vehicle speed, but discharge sound of engine noise is not necessarily proportional to the engine RPM.
Therefore, a degree at which the discharge sound of the engine noise affects the noise inside the vehicle is relatively large at a low engine RPM.
Therefore, in the variable intake system in the related art, two or more air ducts are provided to reduce the discharge sound at a low RPM, and reduce flow resistance of intake air at a high RPM, and a method of mounting valves in some air ducts, selectively closing the valves at a low RPM, and selectively opening the valves at a high RPM is used.
The variable intake system in the related art has a valve assembly for selectively opening and closing some of the plurality of air ducts, and an actuator which provides driving power to the valve assembly, and there are a semi-active type actuator, and an active type actuator.
Here, as the semi-active type actuator, a vacuum type actuator using a solenoid, and a spontaneous opening and closing type actuator using a magnet can be exemplified, and the active type actuator uses a DC motor.
In the related art, there are problems in that there is a spatial problem because the plurality of air ducts are adopted, and costs and weight are increased due to the plurality of air ducts and the expensive actuator.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.